The invention is directed to a branch separating filter in a GHz frequency range, wherein a feeder waveguide is provided which is a plurality of individual filters coupled thereto at electrically significant spacings.
In electrical transmission systems, for example in radio link systems, frequency separating filters are required in the microwave frequency range for reactionless combining or separating of different frequency bands. Critical demands made of these frequency separating filters are: low insertion loss, module structure, no health risk to the personnel due to microwave emission, no interruption in operations when rigging separating filters, and low manufacturing costs.
In addition to containing filters, conventional, modularly constructable chains of channel filters also contain circulators that are relatively expensive, cause undesirably high insertion losses, and can also not always be constructed compactly (Ensslin, G.; Herder, H. H.; Schuster, R.: Kanalweichen fuer Breitband-Richtfunksysterne, telecom report 9 (1986) Sonderheft "Nachrichtenuebertragung auf Funkwegen", pages 203-208). On the other hand, low attenuation and cost-beneficial but not previously modularly constructable frequency separating filters have been disclosed (Pfitzenmaier, G.: Ein Beitrag zur Optimierung und Realisierung von Hohlleiter-Frequenzweichen, Frequenz 29 (1975) 9, pages 253-261). wherein the microwave filters are coupled to a waveguide that is short-circuited at the end ("Manifold Frequency Separating Filter").